Jose Mourinho's biggest mistake so far as Chelsea manager is...

The Portuguese readily admits a striker is a necessity, so why did he let a good one go in the summer?

Chelsea may be fighting for position at the summit of the Premier League table but the manner in which they are doing so, with just six goals scored in five domestic matches, is sub-par when compared with the prolific goal-getting sides such as Arsenal and Manchester City.

Part of that problem is that all of their goals have come from their midfield (or the opposition's foot) as, to date, Oscar (x2), Frank Lampard, Branislav Ivanovic, Oscar and John Mikel Obi are the only players to get onto the scoring charts whilst serving league duty.

While the current campaign is only five games young, a pentad of strikers have separated themselves from their peers as Daniel Sturridge, Sergio Aguero, Olivier Giroud, Christian Benteke and Robin van Persie lead the way in terms of striking efficiency (goals + assists / minutes played) with Aguero the most effective having produced a goal or assist once every 85 minutes.

Last season, Lukaku either scored or assisted 21 times in 2,003 minutes of Premier League action, meaning he was directly effecting West Bromwich Albion's scoreline once every 95 minutes. This season, only Aguero and Giroud are more reliable.

Last weekend served a cold reality check for Mourinho even if the 'Happy One' refuses to admit so to the press.

Eto'o continued his failure to find the net at Everton, even though Chelsea went on to record a 2-0 victory and now, combining that performance with his sub-par showing versus FC Basle, the Cameroon striker seems off-pace, non-threatening and does not have the work-rate that is required of an elite performer in England.

Lukaku at Everton, meanwhile, showed all the gusto that makes Chelsea fans proud of balls-out players like John Terry, David Luiz and Frank Lampard as he headed in a goal, only to end up unconscious. He is now one game into his Toffees career, with one goal to show for it.

Transfer rumour speculation refuses to abate regarding Mourinho's pursuit of a striker, with Robert Lewandowski and Fernando Llorente all linked with a winter window switch to Stamford Bridge, however, would that be such a mandatory - and expensive - requirement had Lukaku not been gifted to Everton?

It must surely be seen as a mistake to allow the burgeoning Belgium to flourish at another club, and a grave one at that as there is no recall clause.

'Lukaku is good at Everton,' said Mourinho recently as quoted by the Daily Mail. 'If he's going to play every game, it's good for his future at Chelsea.'

Considering the dearth of quality striking options coupled with the pressing need for someone in January who can relieve the Blues' midfield of the goal-scoring burden, surely it would have benefited Chelsea's present - not just their future - if Lukaku was good for Chelsea right now, rather than for Everton.